That’s not true. Only “das Radio” is correct Standard German. Only “die Butter” is correct Standard German. Other forms may well be common, and accepted as dial

That’s not true. Only “das Radio” is correct Standard German. Only “die Butter” is correct Standard German. Other forms may well be common, and accepted as dialect. But they’re not Standard German, which means they’re not taught in school (except by mistake), and are not acceptable in official communications. You may not like that German is so overly prescriptivist (I have issues with it) but it’s a simple fact. Additionally, your explanation about the origin of the gender of “Butter” is entirely apocryphal: the original Greek/Latin gender has at best an indirect influence on the gender of the modern German word (and in fact both were neuter: βούτυρον vs butyrum).